This young occasion is localized within the geographic degree associated with La Grange error

23 Feb This young occasion is localized within the geographic degree associated with La Grange error

Rachel Piotraschke, Susan M. Cashman, Kevin P. Furlong, Peter J.J. Kamp, e it on Siletzia?. Lithosphere 2015;; 7 (4): 427a€“440. doi:

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Abstract

The Klamath hills province of northwestern Californiaa€“southwestern Oregon is actually an anomalous element in the Cascadia margin; these hills have the greatest typical topography, the earliest rocks, in addition to merely recognized exemplory instance of belated Cenozoic detachment faulting into the seaside hills in the Cascadia forearc. Low-temperature thermochronology (apatite fission-track, apatite [U-Th]/the guy) analyses through the main and south Klamath Mountains state record two specific exhumation events-a Cretaceousa€“Paleocene local air conditioning and a southward-migrating locus of fast cooling/exhumation in the centre Tertiary. We infer this pattern reflects two specific processes of exhumation: regional area erosion (older) and migrating localized tectonic exhumation (younger). During the south restrict of this region of rapid cooling, slickenside striations in the subjected Los Angeles Grange mistake exterior record southward displacement associated with the upper plate along a shallowly dipping (a??20A°) detachment surface. Thermochronologic data constrain ordinary dip of failing to a few levels, upper-plate width to

INTRODUCTION

The Klamath hill province (Fig. 1) straddles significant changeover from inside the united states plate boundary from subduction along Cascadia to interpretation across the San Andreas system, and it’s really both geologically and topographically unique. The orogen’s Neogene to Holocene tectonic record potentially produces a window to the advancement in the plate boundary whilst underwent the transition from an extended history of subduction (Farallon, Juan de Fuca) to encroaching translational (Pacific) dish connections. The Klamath hill state presently hosts a few of the greatest geography across the convergent border (Fig. 1A). Max and imply elevations during the Klamath Mountains were higher than those elsewhere from inside the seaside range of Cascadia (Kelsey et al., 1994), therefore the Klamath hill province, composed of Precambrian to Late Cretaceous, primarily oceanic tectonostratigraphic terranes, include the oldest (Wallin et al., 1995) and among the most structurally complex (cf. Irwin, 1981, 1985) products along the Cascadia margin. The time when this highest geography created and union between uplift and exhumation of Paleozoic and Mesozoic bedrock remain ambiguous.

Active distortion within the southernmost Cascadia subduction region, during the latitude with the Klamath hills state, furthermore differs from regarding all of those other Cascadia margin.

Models of seismicity, such as the spatial and temporal distribution of episodic tremor and slip activities (Fig. 1A; Szeliga et al., 2004; Brudzinski and Allen, 2007; Gomberg et al., 2010; K. Creager, , personal commun.), anticorrelation of tremor and tiny upper-plate earthquakes (Boyarko and Brudzinski, 2010; Gomberg et al., 2010), and inferred segmentation of Cascadia subduction zone quake record (age.g., Wang et al., 2013), all separate the south a portion of the Cascadia subduction region.

(1) Does the Klamath topographic massif mirror relict (later Cretaceousa€“Early Tertiary) topography, or perhaps is it a direct result youthful and/or ongoing uplift from the modern plate boundary?

(2) Do the unique seismologic personality in the southernmost Cascadia subduction area margin mirror the geologic fictional character on the local forearc (e.g., crust for the Klamath hill state), or will they be just a function of the present plate-tectonic setting separate of upper-plate crustal structure?

In this papers, we present newer low-temperature thermochronologic information from central and southeastern Klamath Mountains, use these to constrain the activity reputation of a regionally significant fault (the La Grange failing), and determine her effects when it comes to Cenozoic tectonic evolution regarding the Klamath hills province. With brand-new thermochronometry information, we taste previous perceptions of Cenozoic reputation for the Klamath part, e.g., Neogene Condrey Mountain dome (Mortimer and Coleman, 1985) and Klamath peneplain (Diller, 1902; Aalto, 2006). We after that talk about the spatial and temporal correspondence between mid-Cenozoic tectonic activities during the Klamath Mountains state and the accretion associated with the Siletz terrane within the Oregon coastline Ranges (Wells et al., 2014). We determine that Cenozoic tectonism in the Klamath hills province was actually connected to occasions on Cascadia margin on the north.